1. Field of the Invention
The present invention relates generally to the field of operating mechanisms for electrical switches and more particularly to an improved linear operating mechanism that operates in accordance with the basic principles disclosed in the aforementioned, commonly-assigned, copending application Ser. No. 721,613.
2. Description of the Related Art
Various operating mechanisms are utilized to operate switches and the like between open and closed positions. In particular, operating mechanisms are desirable for switch applications that store operating energy to selectively close a switch and to immediately thereafter be capable of opening the switch as required.
A first variety of operating mechanism provides for the charging of an opening spring during the switch closing operation. Examples of this type of mechanism are disclosed in the following U.S. Pat. Nos. 4,453,056; 4,121,077; 4,105,878; 3,898,409; 3,845,263; 3,835,277; 3,784,764; 3,728,508 and 3,600,541. This type of operating mechanism requires a higher-capacity closing spring to perform the functions of both closing the switch and charging the opening spring. The requirement of a higher-capacity closing spring is, of course, undesirable since it also requires higher-capacity latching, driving, and supporting arrangements, as well as high speed latch engagement for the opening components.
Another variety of operating mechansim requires the detaching of the closing spring from the operating member during switch opening. This type of operating mechanism requires a relatively complex arrangement for the required detaching of the closing spring. U.S. Pat. No. 3,876,847 discloses an arrangement that sequentially charges the closing spring and then the opening spring; the arrangement also including the detaching of the closing spring during switch opening.
An operating mechanism that avoids some of the drawbacks of the aforementioned approaches is disclosed in U.S. Pat. No. 4,124,790. The arrangement as seen in FIGS. 5 and 8 of that patent includes a closing spring 75 connected between a drive lever assembly 70 and the frame, and an opening spring 76 connected between the drive lever assembly 70 and a switch operating lever assembly 69. The springs 75 and 76 are charged by movement of the drive lever assembly 70. A separately biased, toggle lever assembly 71 acts between a pivotal lever arm 77 of the switch operating assembly 69 and a pivotal lever arm 123 of the drive lever assembly 70. The pivotal lever arm 77 is connected through linkage 72 to operate a switch. When the springs are charged, the drive lever arm 123 is latched by a plate 147. The toggle lever assembly 71 is latched by means of a latch that is operative to maintain the pivotal toggle arms 95 and 97 of the assembly 71 in the latched position. The lever arm 77 is held in position by the latched, toggle arms 95,97 acting against the latched drive lever arm 123. To close the switch, the drive lever arm 123 is unlatched, whereupon the closing spring 76 pivots the arm 123 counterclockwise with the lever arm 77 being correspondingly pivoted counterclockwise through toggle arms 95,97. The pivoting of the lever arm 77 closes the switch. To open the switch, the latch on the toggle arms 95,97 is released. As the toggle arms 95,97 collapse, the opening spring 76 pivots the lever arm 77 in the clockwise direction. This configuration is complex and is neither suitable nor desirable for many applications. For example, the switch operating drive lever assembly 69 is only indirectly latched through the collapsable toggle lever assembly 71. Further, the arrangement to latch the toggle lever assembly 71 is complex and requires a latching element that operates against moving latching surfaces. Accordingly, the arrangement of U.S. Pat. No. 4,124,790 includes complex, indirect latching and a complex arrangement to transmit force and movement from the drive lever member 123 to the switch operating member 77.
U.S. Pat. Nos. 3,913,459, 3,835,277 and 3,646,292 disclose the advantageous use of ring latches for releasably restraining a movable member in the operating mechanism and other apparatus.
While the aforementioned arrangements are generally useful and satisfactory for their intended use, it is desirable to provide an improved operating mechanism with improved operational features.
An improved operating mechanism is disclosed and claimed in commonly-assigned, copending application Ser. No. 721,613 filed in the name of Chester H. Lin on Apr. 10, 1985, and now U.S. Pat. No. 4,578,551 . While the operating mechanism disclosed therein is entirely suitable for many types of switch operating applications, the present invention is directed to an improved linear operating mechansim of the basic type disclosed in the aforementioned application and that includes particular features that are desirable for certain switch operating applications including linear motion, compact design, the control of three phases of a switch arrangement, and the requirement for higher operating forces.